Despite gel electrolytes' high ionic conductivity and appreciable mechanical softness making them promising candidates for flexible electronic devices (FEDs), preparing gel electrolytes which seamlessly interface with electrodes is still challenging, especially via rapid gelation. Inspired by cartilage, a mechanically interlocked and hydrogen bonded electrolyte–electrode interface (MHEEI) generated using an ultrafast gelation process via in situ interfacial polymerization of gelatin macromolecules and acrylamide monomers hybrid fluid is reported. A nanoporous carbon (NC) electrode favorable for polymer matrix embedding is employed to lock into the in situ gel electrolyte through a mechanical interlocking structure. Polyacrylamide chains inside the nanoporous electrode are strongly connected with gelatin chains via intra-intermolecular hydrogen bond interactions. Their synergy simultaneously imparts low contact resistance (1 Ω), high ionic conductivity (55.9 mS cm⁻¹) and interfacial toughness of 16 J m⁻² at MHEEI, which is 6.4 times greater than that obtained by a physical stacking approach. The NC electrode with MHEEI thus exhibits a specific capacitance of 336 F g⁻¹ (at 8 A g⁻¹), about 12 times greater than that of the electrode with MEEI. Additionally, an interrupted electronic circuit is instantly restored via ultrafast construction of interlocking layers. This concept can be demonstrated in other gel systems, providing generalized design principles for the ultrafast construction of interlocking structures for FEDs.